Nutrient profile | Fats
Quality counts.
Image credit: Faiha Firaq via pinterest.com.au
Nutrient type Macronutrient
Overview Some fats (lipids) are essential for maintaining good health, whilst others are implicated in the development of multiple chronic diseases; thus, striking a healthy balance is key. Fats may be saturated or unsaturated; although they most definitely have their place as part of a balanced and healthy diet, saturated fats - found in animal fats, butter and cream, for example - contribute to the development of cardiovascular and metabolic diseases, and are therefore best enjoyed only occasionally. Meanwhile, unsaturated fatty acids are associated with myriad health benefits and should ideally feature alongside complex carbohydrates and lean protein in every meal. Unsaturated fats may be monounsaturated or polyunsaturated; the latter includes essential fatty acids, omega-3 and omega-6 [1; 2].
Omega-6 and omega-3 fatty acids and their precursors (known as linoleic acid (LA) and alpha-linolenic acid (ALA), respectively) are considered essential inclusions in the diet, as the body is unable to produce them on its own. Whilst both support essential functions in the body, omega-3s offer greater health benefits, helping to lower blood pressure, prevent blood clot formation and reduce inflammation. As omega-6 fatty acids are generally more accessible in the diet, and the conversion of ALA to omega-3s EPA and DHA is neither consistent nor efficient (at a rate of 5 to 8 per cent), achieving an adequate dietary intake of pre-formed omega-3s is particularly important, and generally requires greater attention [1; 2; 3].
Rich food sources
Nuts and seeds, extra virgin olive oil, flaxseed oil, avocado and oily fish are all rich sources of monounsaturated and polyunsaturated fatty acids.
LA (converted to omega-6 fatty acids) is found in many nuts and seeds, including walnuts, pine nuts, pistachios, sesame seeds (and tahini), poppy seeds, sunflower seeds, pumpkin seeds, almonds and cashews, as well as flaxseeds (and flaxseed oil).
Omega-3 fatty acids are found in oily fish varieties including Atlantic salmon, ocean trout, mackerel, anchovies and sardines.
Flaxseeds and walnuts contain ALA, which the body can convert (albeit in limited amounts) to omega-3. Rich vegan sources of omega-3 include some types of seaweed and micro algae, which can be taken in supplement form [4].
Functions and benefits
Lipids are the most energy-dense of all macronutrients; they provide energy for both muscles (during rest and light exercise) and intestinal cells. Stored lipids (in adipose tissue) can be mobilised to produce energy when needed, and also protect body organs and insulate the body against changing temperatures.
Lipids form part of cellular membranes and support cell signalling and metabolism.
Lipids also support gastrointestinal function, stimulating the production and release of bile (to aid digestion) and supporting the absorption of fat-soluble nutrients (vitamins A, D, E and K).
Monounsaturated and polyunsaturated fats promote satiety.
Longer-chain, essential fatty acids (omega-3 and omega-6) support the production of specific metabolites known as eicosanoids, which are involved in particular pro-inflammatory and anti-inflammatory responses in the body, along with blood pressure and circulation, blood clotting and reproductive health. Omega-6-derived eicosanoids promote inflammation, blood clot formation and blood vessel constriction, whilst omega-3 fatty acids help to reduce inflammation, prevent clot formation and lower blood pressure.
Essential fatty acids also help to strengthen the skin barrier, helping to reduce skin permeability, dryness and dehydration.
They also form part of the brain structure and nerve fibres, and are therefore essential for both healthy brain development and vision in children, in particular.
Essential fatty acids are also critically important for calcium and bone metabolism; they increase calcium absorption and deposition in bone, and improve bone strength [1; 2].
Storage in the body Lipids that exceed the body’s requirements are stored in adipose tissue [1].
Signs and symptoms of inadequate fat intake
Deficient intake of essential fatty acids may lead to excessive thirst and/or perspiration, skin dryness and/or rashes, dry hair, nail weakness, and/or chronic inflammation.
Possible indicators of insufficient intake of omega-3 fatty acids in particular, include:
Cardiovascular conditions (e.g. high blood pressure and/or cholesterol, cardiac arrhythmia)
Autoimmune conditions (e.g. rheumatoid arthritis)
Neurological conditions (e.g. mood disorders, depression)
Reproductive conditions (e.g. premenstrual symptoms, menstrual irregularity)
Osteoporosis
Chronic inflammatory conditions (e.g. osteoarthritis, asthma, hay fever) [2].
Recommended fatty acid intake
Dietary guidelines suggest that 20-35 per cent of an individual’s daily energy requirements are met by lipids [1].
Adequate intake (AI) | Omega-3 fatty acids
Women (19-70+ years): 90 mg/day
Men (19-70+ years): 160 mg/day
Children:
Girls: 40 mg/day (1-3 years); 55 mg/day (4-8 years); 70 mg/day (9-13 years);
85 mg/day (14-18 years)Boys: 40 mg/day (1-3 years); 55 mg/day (4-8 years); 70 mg/day (9-13 years);
125 mg/day (14-18 years) [5].
Note. Adequate intake (AI) is used where a RDI cannot be determined; AI refers to the minimum level of intake of a particular dietary nutrient that is considered unlikely to be inadequate. It is based on the approximated / estimated average intake of the nutrient for particular groups of apparently healthy people [4]. As such, individual requirements may differ.
Indicative (approximate) serving sizes - examples only
1 grilled Atlantic salmon fillet (~150g) provides ~3,675 mg omega-3 fatty acids
Note. Enjoy one serving of Atlantic salmon each week for a therapeutic dose of omega-3 fatty acids].
Five anchovy fillets (~20 g) provides ~153 mg omega-3 fatty acids
Half an avocado offers ~7g monounsaturated fatty acids
One tablespoon of extra virgin olive oil provides ~12g monounsaturated fatty acids
One tablespoon of flaxseed oil offers ~2.6g LA (omega-6 precursor) and ~10g ALA (omega-3 precursor).
A quarter cup (approx. 30g) of raw, unsalted walnuts provides ~13g LA (omega-6 precursor) and ~1.9g ALA (omega-3 precursor) [4; 5].
Recipes to try | Healthy fats
Roasted eggplant with tahini dressing, by Yotam Ottolenghi (https://ottolenghi.co.uk)
Made from ground sesame seeds, tahini is a wonderful source of omega-6 fatty acids, as well as vitamin E and calcium.
Fennel, pear and ocean trout salad with horseradish mayo, by Jessica Cox (@jescoxnutritionist)
Oily fish varieties such as ocean trout are rich in both omega-3 fatty acids and protein.
Greek salad dressing, by Cookie + Kate (@cookieandkate)
Extra virgin olive oil is a wonderful source of monounsaturated fatty acids, alongside many other beneficial polyphenols (antioxidants). Individuals who are unable to consume animal-based sources of omega-3 fatty acids could try substituting extra virgin olive oil for flaxseed oil, rich in ALA (the precursor of omega-3 fatty acids), although a (plant-based) supplement may also be required.
Other notes
The traditional Mediterranean diet – associated with longevity and some of the lowest rates of inflammatory disease, worldwide – is characterised by an omega-6/omega-3 ratio ranging from 1:1 to 2:1. A ratio of 1:1 to 4:1 is recommended to promote health and increase anti-inflammatory activity in the body. The typical Western diet far exceeds this ratio, reaching up to 15:1 to 20:1.
As LA and ALA compete for conversion to omega-6 and omega-3, respectively, via the same enzyme, consuming pre-formed sources of omega-3 and omega-6 will most effectively maintain healthy levels of these nutrients [1].
References.
[1] Whitney, E., Rolfes, S., Crowe, T., & Walsh, A. (2019). Understanding nutrition (4th ed.). Cengage Learning Australia Pty Limited.
[2] Paxton, F. (2015). Foundations of naturopathic nutrition: A comprehensive guide to essential nutrients and nutritional bioactives. Routledge.
[3] Burns-Whitmore, B., Froyen, E., Heskey, C., Parker, T., & San Pablo, G. (2019). Alpha-linolenic and linoleic fatty acids in the vegan diet: Do they require dietary reference intake / adequate intake special consideration?. Nutrients, 11(10), 2365. https://doi.org/10.3390/nu11102365
[4] Food Standards Australia and New Zealand. (2021). Australian Food Composition Database. https://www.foodstandards.gov.au/science/monitoringnutrients/afcd/Pages/default.aspx
[5] Australian National Health and Medical Research Council and New Zealand Ministry of Health. (n.d.). Fats: Total fat & fatty acids. Nutrient Reference Values for Australia and New Zealand. Retrieved February 2, 2023, from https://www.eatforhealth.gov.au/nutrient-reference-values/nutrients/fats-total-fat-fatty-acids